This invention relates to an inflatable restraint system, commonly referred to as an airbag system, which, when used in an automobile, will restrain the movement of a seated occupant in the event the vehicle is involved in a collision. More particularly, the invention is directed to an improvement in the structure for housing the inflator and cushion of such a system.
Airbag systems typically involve an inflator, which upon actuation by a collision sensor located somewhere on the vehicle body, rapidly produces a sufficient quantity of gas to inflate an associated cushion which rapidly expands to occupy the space between an occupant of the vehicle and one or more of the interior surfaces of the vehicle. The primary airbag system provided to protect automobile passengers (as contrasted with those to protect the driver) is typically located behind the instrument panel, or dashboard. Often such a passenger airbag system is intended to protect two passengers and is located further from the passengers than is the typical driver side airbag. Such a passenger side airbag system, therefore, has a larger cushion and requires a greater quantity of gas for its inflation. The limited space available, combined with the requirement for a relatively large gas output, dictates that inflators used with such systems typically are in the form of elongated cylinders mounted transverse to the direction of cushion deployment. Such inflators are typically provided in a trough like compartment provided at the rear of a housing. The folded airbag cushion is mounted between the inflator and an opening at the front of the housing. Examples of such housings are disclosed in commonly assigned U.S. Pat. Nos. 4,941,678 to Donald R. Lauritzen, Michael J. Ward and Scott R. Anderson; 5,332,256 to Donald R. Lauritzen and Bradley W. Smith; 5,387,009 to Donald R. Lauritzen and Larry D. Rose; 5,405,164 to Donald J. Paxton and David J. Green; 5,431,436 to G. Dean Mossi and Brett R. Garner; 5,435,595 to Donald R. Lauritzen, Donald J. Paxton and Larry D. Rose and 5,441,705 to Donald R. Lauritzen, David J. Green and Larry D. Rose. One type of recognized inflator design discharges the product gas at one end of its cylindrical structure. Typically such design is associated with so called hybrid inflators which function by igniting a solid pyrotechnic material which then heats a compressed inert gas producing an enhanced volume of gas product. Examples of such inflators are disclosed in commonly assigned U.S. Pat. Nos. 5,360,232 to William G. Lowe, Walter A. Moore and Linda M. Rink; 5,378,015 to Linda M. Rink, William G. Lowe and Daniel R. Leininger; 5,421,609 to Walter A. Moore, Leland B. Kort and Kelly B. Johnson; 5,425,550 to Donald J. Paxton, Bryan D. Matzl and David J. Green and in previously mentioned U. S. Pat. No. 5,405,164. The recently developed fluid fuel inflators also use an inflator design wherein the product gas is discharged at one end of its cylindrical structure. Such inflators are described in commonly assigned U.S. patent application Ser. No. 08/252,036, entitled FLUID FUELED AIRBAG INFLATOR, and filed on May 31, 1994 by Bradley W. Smith and Karl Rink now U.S. Pat. No. 5,470,104. The above mentioned commonly assigned patents are incorporated by reference herein. The use of the described inflator in the described housings requires that the gas be redirected and distributed into the interior of the cushion. Since the gas is discharged at only one end of the inflator, the cushion tends to fill preferentially at the same end and is undesirably skewed as it deploys. In the past, various methods, including the use of baffles, retainers, diffusers, tethers and plenums have been used to correct such skewed deployment of the cushion. Examples of such are found in U.S. Pat. No. 5,340,147 to Robert P. Fontecchio et al. and commonly owned U.S. Pat. application Ser. No. 08/280,894 filed by John C. Newkirk, Larry D. Rose, Donald R. Lauritzen, Michael J. Ravenberg, Mark A. Thompson, David J. Green and Terry R. Davis. These techniques have generally added extra cost and/or reduced the available cushion packaging space of the module.
It is an object of this invention to provide an economical plenum and reaction canister, or housing, for use with inflators which discharge their product gas at one end thereof. It is a further object to provide an airbag module using such a plenum and housing. More specifically, it is an object of this invention to provide a plenum which effectively controls the deployment skew associated with end discharge inflators without adding cost to the module, without adding significant gas flow restrictions or sacrificing cushion packaging space.